The present invention relates generally to devices used for testing vacuum systems for leaks or restrictions. More particularly, the present invention relates to devices which can be inserted in a vacuum system and which measure the vacuum pressure at a flow rate generally equal to the flow rate of the vacuum system running at operating conditions.
Vacuum systems are currently in wide-spread use throughout the die casting industry. A vacuum system is attached to a die casting machine to reduce casting porosity caused by trapped gas. This is accomplished by drawing the air out of vacuum lines and die cavity, which creates a vacuum at the cavity opening. Casting material is placed in the opening, and the machine plunger then forces the material into the cavity.
Vacuum systems are generally made up of a vacuum pump, an air-tight holding tank and a series of lines, valves and filters. When the vacuum pump is running, air flows freely through the system. The flow rate is determined by the vacuum pump, line size, die cavity size and die parting lines.
When leaks or restrictions develop in a vacuum system, the flow rate decreases and the vacuum die casting process is not properly applied. The resulting castings are of inferior quality. Without proper vacuum at the die cavity, the casting material can trap air or gas in the mold. In order to correct the problem, the die casting machine must be shut down and the leak or restriction must be isolated and fixed before production can continue. Any component of a vacuum system can become restricted, and therefore it is very difficult to isolate which component is responsible for the problem.
Currently, troubleshooting a problem in a vacuum system is accomplished by attaching a vacuum gauge at the point where the vacuum system attaches to the die block. Static pressure in the lines is then measured to determine if the problem is in the vacuum system or the die casting machine. If the problem is in the vacuum system, parts must be replaced one by one until the system is operating properly, or the entire system must be dismantled and inspected in order to find the problem.
One disadvantage of the current tools and methods of troubleshooting a vacuum system is that only static pressure in the lines is measured. The vacuum system is never tested while running at actual operating conditions.
Another disadvantage of current vacuum system trouble-shooting tools and methods is that it is often difficult to isolate the exact location of a problem. Also, the current tools are hard to install and cannot be used to help pinpoint faulty components.
Yet another disadvantage of current tools and methods is that they are often inaccurate. Often leaks or restrictions are not readily apparent, or the system is misdiagnosed as having leaks or restrictions which it does not actually have.
Still another disadvantage of the current tools and methods is that they are not specially tuned for the vacuum system they are made to troubleshoot. This makes it difficult to determine where the problem is, and often leads to misdiagnosis of the problem.
Thus, it is an object of the present invention to provide an improved vacuum system testing tool and method which checks the line pressure of a vacuum system running at actual operating conditions.
It is another object of the present invention to provide an improved vacuum system testing tool and method which will decrease the down time of die casting systems by making it easier to locate and fix faulty components of the system.
It is yet another object of the present invention to provide an improved vacuum system testing tool and method which is more accurate than previous tools and methods.
It is still another object of the present invention to provide an improved vacuum system testing tool and method which is specially tuned for the vacuum system in which it is used.
Other features and advantages of the present vacuum system testing tool will be apparent from the following description taken in conjunction with the accompanying drawings.